Host: The Japan Radiation Research Society
Co-host: Asian Association for Radiation Research
Mutation in DNA is deleterious for maintenance of each individual. On the other hand, it is necessary for keeping variability of individuals. Thus, it is an interesting question to ask weather or not DNAs in somatic cells and germ-line cells are maintained in a same way. One of the approaches to answer the question is to examine mutations in these cells. Here, we compared spontaneous mutations in gonadal and somatic tissues in mouse embryo. We used lacZ-transgenic Muta(TM) mice. Mutants were selected as P-gal resistant lambda phage clones after retrieving lacZ-containing lambda DNA from mouse genome by a use of packaging procedure. To understand the molecular nature of mutations, the lacZ genes of mutants were sequenced and compared to the sequence of wild type gene. Testes and ovaries were separated under binocular from 14.5-day embryos. The remaining embryos were used as somatic tissues. The mutant frequencies in the male and female gonads were similar; about 3×10-5. They were slightly lower than the level in the somatic tissue. The molecular nature of mutation as judged by spectrum of different kinds of mutation showed similarity among the tissues. The detailed analysis of deletion mutation, however, revealed a difference in the size of the deleted sequences between the gonads and the somatic tissue. It suggests that the genome maintenance system in germ-line cells is not the same as that working in somatic cells.
